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914World.com _ 914World Garage _ Is Megasquirt the right one

Posted by: lmcchesney Jul 14 2006, 03:00 PM

I have given up on adapting my 2.0L D-jet FI for the new engine. From what I have read, I believe that the MS FI system would be an acceptable alternative. My engine is a 94 x 78 with a stroker crank and Web cam 73, 2.0 stock njectors each flowing about 45ml/min and balanced. The heads are mild to moderate ported with 48mm intake and 38 exhaust. Regular ignition system with standard distributor. I have increased the volume of the fuel rales and bumped the pressure to 38PSI with a dual parallel fuel pump system. I have tried to enhance the D-jet system and have a variable resistor between the CHT and ECU. I have tried to adjust the system using a CO monitor. I have added an external oil cooler and the temps run about 100-150 degrees with a pressure of 1-3 Bar. It runs well in the low end with a ruff idle but acceptable. However, it flattens out at high rpms (5000) and acts like it starving for fuel at WOT.
I believe that MGS FI system would allow me to optimize the engine and prolong life of the engine as well. Additionally, can you use the CO monitor in place of the wideband AF monitor?
Additional questions are as to advantage of the megasquirt II, placement of the ECU in the engine compartment, rear trunk or in the cab. Your thoughts would be appreciated.
Larry

Posted by: jkeyzer Jul 14 2006, 03:04 PM

Put the ECU in the cab. Mine is between the seats. This keeps it away from moisture and heat. The rear trunk would work too, but you'll need to get a serial cable long enough to go into the cabin for tuning.

Get a wideband O2 sensor, you will need it.

Megasquirt will do what you need much better than stock D-jet, but you will need to be comfortable with fuel injection and electronics, or willing to learn! It takes a lot of time to set up so be prepared to mess with the settings.

MSII is probably not required but it makes life a little easier, sensor calibration no longer requires reflashing the ECU and there is builtin ignition support.

Posted by: lapuwali Jul 14 2006, 03:15 PM

The rear trunk is actually too hot, at least for MSI. The exhaust really heats up the trunk, often to higher temps than the engine bay.

There aren't any CO monitoring systems that work in real time at all engine loads while the car is in motion, at least not that I know of. Wideband O2 is what you want.

btw, 100-150 degrees (F) is too cool for oil, so you're overcooling the engine, robbing some efficiency. You should add an oil thermostat. You want oil temps of 180dF to 220dF.


Posted by: Aaron Cox Jul 14 2006, 03:40 PM

However, it flattens out at high rpms (5000) and acts like it starving for fuel at WOT.

[/quote]

web 73 cam is the djet cam right? stock cam falls off at 4500 ish... and looks like the web is the same.....

and yes. get a thermostat. your oil is too cold

Posted by: yarin Jul 18 2006, 08:15 PM

I went with megasquirt II, I absolutely love it.

Trunk might not be too hot for MSII but I would put it elsewhere. I put my relay box behind the driver seat in the engine compartment and the brain under the dash infront of the shifter with the cable running on top of the tunnel.

Buy a wideband O2 sensor - Innovative LC-1 for $200. Best bang for the buck. I really like their platform. Weld a bung on your exhaust and tune to your hearts content.

Cheers

Posted by: Bleyseng Jul 18 2006, 08:32 PM

You can tune the Djet to work it just takes time.

The MPS's must be opened up so you can adjust the damn thing.

I can adjust it so I get a rock steady 12.5 to 1 all the way up to 6500rpms. It does start at 11.5 to 1 when you stomp on the gas but then levels out nicely. On a stock 2.0L the cam and valve springs crap out at 4500rpms. A better cam and HD springs help alot to change that and give you hp in the high rpms. Yes, the djet can keep up.

I can adjust the MPS to give me 9.5 to 1 so there is LOTS of fuel availble.

I wish you were closer so I could lend you a hand.

There are NO easy short cuts to tune the EFI whether its Djet or MS, Haltech etc.


Maybe in the next year there will be some off the shelf MS units ready to go but that still wouldn't help you.

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